The tally of people killed in Wisconsin car crashes dropped significantly in 2013, with the low numbers rivaling World War II-era totals, preliminary data from the state Department of Transportation shows.

In 2013, 527 people lost their lives on Wisconsin roads, compared with 601 deaths in 2012. There also were 19,000 fewer crashes overall.

That means 2013, when official counts are released later this summer, likely will have the lowest number of traffic-related deaths since 1944. Only two years, both during World War II, have recorded fewer fatalities since cars became widespread in the modern era: 1944 had 526 deaths; and in 1943, there were 417 deaths.

These statistics are especially astonishing considering that within this 70-year period, automobile travel exploded. Deaths were fewer during World War II, but people drove less, so the fatality rate was about 10 times higher than today.

Large drops in passenger and motorcyclist deaths accounted for much of the 12% plunge from 2012 to 2013, said Don Lyden, a safety research analyst for the DOT.

With extended wintry weather shortening the motorcycle-riding season in 2013, crashes killed 84 motorcyclists, down from 116 the year before, he said. In vehicles, 388 people died in 2013 compared with 430 in 2012, an 11% decline due to fewer accidents with multiple fatalities and fewer passengers dying.

Pedestrian deaths also were down 16%, from 44 in 2012 to 37 last year. Other categories make up the remainder of the 2012 and 2013 totals.

Since the 1980s, traffic-related deaths in Wisconsin ranged between 700 to 800 a year, but they dropped sharply during the last recession into the 500 to 600 range. Deaths have risen since 2009, however, and this will be the first year to interrupt that trend.

Transportation officials have attributed the general decline in deaths over time to increased safety measures, such as higher rates of seat belt compliance and better infrastructure, but specific reasons for why deaths are down this year isn't clear. For example, the reduction in accidents with multiple fatalities might just be a matter of crashing a few feet farther to the left or to the right, Lyden said.

"Why is everyone else's guess," he said. "In the end, if you avoid those multiple fatal ones, you got lucky, and by avoiding them this time, we did better."

DOT Secretary Mark Gottlieb said there was no single factor for such a significant reduction.

"We know that the vast majority of serious crashes are caused by bad driving habits and irresponsible decisions," he said. "Therefore, motorists deserve a great deal of credit for saving their own lives and lives of others by slowing down, paying attention, buckling up and driving sober."

The seat belt compliance rate has risen to its highest ever, 82% in Wisconsin. That probably saved some passengers' lives. Even so, Wisconsin lags neighbors such as Illinois and Michigan, where compliance is more than 90%.

It's too early to know how much effect drunken driving played in the 2013 crashes. Alcohol was a factor in more than 40% of crashes in the five-year period from 2008 through 2012.

Zero in Wisconsin, the state's campaign to reduce traffic deaths to zero, lasted only five hours for 2014. The first fatal crash was reported at 5:10 a.m. on Wednesday in St. Croix County.

The reduction in crashes saved about $237 million, an estimate that factors in medical expenses, higher insurance premiums, lost wages and other factors, says David Pabst, director of the DOT Bureau of Transportation Safety.

A National Highway Traffic Safety Administration statistical projection for the first half of 2013 predicted a 4% decrease in deaths nationally.

Gail Weinholzer, a AAA spokeswoman, said higher fatalities in 2012 nationally were partly due to dramatic increases in pedestrian, bicycle and motorcycle fatalities, even as driver fatalities fell.

"We're finding that people are walking and biking more, whether for gas prices or for health reasons, or it's just a trend in society, so we've had more (nonvehicle) deaths in general," Weinholzer said. "Beyond that, we've seen an increase because distraction is affecting them like everyone else, and walkers and bikers are engaging in some of the dangerous behaviors auto drivers do, as well."

The year that Wisconsin saw the most deaths from crashes was 1972, at 1,168.